Concrete is a composite material made from aggregates, such as sand and gravel, bound together with a binder such as cement. Typically, aggregates are obtained from mining combined with a crushing operation to produce particulates of a desired size. However, mining operations can disrupt the local environment and mines are often located far from population centers that require large quantities of aggregates.
With increasing concern over the excessive exploitation of natural aggregates, recycled aggregates have been explored as a new source of aggregate material with a goal of sustainable development. Sources of recycled aggregates include construction waste such as recycled concrete aggregates and recycled red brick aggregate; these are used to produce concrete products, such as low grade concrete and non-load bearing concrete blocks. Using construction waste to produce eco concrete blocks has been successfully implemented in various regions and is gaining wider acceptance. However, the present eco concrete block products show a limited fire resistance, especially those with relatively high strength, limiting their use in applications with the most stringent fire resistance requirements, for example, multiple-hour fire resistance. With increasing concern regarding the fire safety of modern buildings, especially high-rise buildings, there is a demand for improved fire resistance of building materials. Thus, there is a need in the art for fire-resistant concrete blocks that include waste material.